Receiver tuning control



Feb. 6, 1940.

D. E. FOSTER RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6 Sheets-Sheet1 @sns/e www ATTORN EY Feb. 6, 1940. D. E. FOSTER 2,189,282

RECEIVER TUNING CONTROL Filed Deo. 23, 1935 6 Sheets-Sheet 2 INVENTORDUDLEY E. FOSTER AT`TORNEY Feb. 6, D, E, FOSTER RECEIVER TUNING CONTROLFiled neo. 23, 1935 6 Sheets-Sheet 3 lNvENToR DZ/LEY E. FOSTER BY 7M wwArToRNEY v Feb. 6, 1940. D. E. Pos1-ER 2,189,282

RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6 Sheets-Sheet 4 INVENTORDUDLEY E. FOSTER BY vw@ ATTO R N EY Feb. 6, 1940. D. E. FOSTER IRECEIVER TUNING CONTROL 6 Sheets-Sheet 5 Filed Dec. 23, 1935 foo Feb. 6,1940. D. E. FOSTER RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6Sheets-Sheet 6 m 2 mw n i mf m l WF.. v` O y 2 o m w. M

'Patented Feb. 6, 1940 UNITED- STATES iaii'itrzlvi' OFFICE 2,139,282 oRECEIVER TUNING' coN'rRoL` Dudley E. Foster, Orange, N. J.,assignorvtoRadio i m.

Corporation of America, a corporation of `Delai Ware x ApplicationDecember 23, 1935,` Serial No; 55,'4749 24 claims. (c1. 250%20) u d iu.:

. ,My `present invention'relates` to radio receiver `tuners, and moreparticularly to novel and imf "proved arrangements for accuratelyadjusting, in a simplewnianner, the tuning deviceof a radio receiver ofthe superheterodynetype.`

r.In the past,` radio receivers Ahave been tuned j' by variationcf thecapacity of the receiving cir-` cuit'throug'h the medium of a reductiongear tun- `ing knob. This hasbeen necessary because of 'the highselectivity provided by modern broadx o `'cast receivers, andparticularly receivers of the superheterodyne type. i Moreover, theaddition of automatic volume `control "to modern receivers `has resultedin rendering the tuning `compara- -.tive difficult in spiteofthereduction ratio of the mechanical drivebetween the-tuning device and bythe use of auxiliary devices. Accordingly, it"l will be seen that thereduction. ratio tuning mech,-`

anism, necessitated by modern receiverselectivy ity, not only results-inslow and tedious tuning operation, but also gives rise to inaccuraciesin "such tuning. j

Automatic frequency control (AFC hereinafter) for a superheterodynereceiver has been previously known; this control tends to automaticallycenter the received signal in the I. F.

` (intermediate frequency) reception band. However, the tuning`operation is greatlysirnplied by the `utilization of the AFC.Therefore, advantage may be taken of thisqfact .to simplify the tuningmechanism for the purpose of obtainingease and rapidity yo tuning.

Accordingly;` it may bestated that itisone of the primary objects of mypresent invention to take full advantage of `the utilization of AFC in areceiver of the superheterodyne type, and` to pro- @vide a manuallyadjustable tuning mechanism whichl enables the userrapidly towchange4the setting of the tuning device to any point required for reception ofa desired'signal.

Another important object .ci the invention is` to `provide an'instantaneous selector device in mechanicalassociation with the tuningcondenserY mechanism, and wherein the selector may )be adjusted to ypositions corresponding to.' predetermined station settings ofthe tuningcondenser;

an'AFC network inthe receiver functioning to "9. remove the necessityfor mechanical accuracy o imposed by modern receiver selectivity.

In practical operationvthe employment'oi' the v e uf maticlvolumecontrol is utilized. `1 l AFC network gives rise toa so-called carryover diculty. Since the AFC tends to keepjthe local oscillator frequencyconstant over an ap preciable range of variation of the tuning con-o`denser, if a signal is brought Within the recepf5 tion band the AFC`functionsfto maintain the oscillator frequency such that this signalonly givesfthe correct intermediate frequency. Hence,v

it will-be' seen that inturiing a receiver equipped `with AFC, thestation signal ilrst operating the ft/10 -control vvill 4be held afterthe tuning condenser position corresponding to` an adjacent signal`channel has been passed over. This carry overv action; in brief,arisesby-virtue of the AFC causing a shift in the localoscillatorfirequency to`-15 l 'such an extent that one 'receivedcarrierwillcontinue the operation of the AFC to the `exclusion l of'oneor more adjacent carriers.

Further'investigation connectedwith the 4ern- `bodimentof 'AFC inasuperheterodyne receiveniBo and'thesimplificationof` the tuningoperation,

yhas resulted in an altered conclusion 'Withrelspect tothe correlation'of the tuning mechanism and the functioning of the AFC network. Ithasbeen found that in order definitely to ensure rer-25.25 1.,-,

ception of'desired stations, the AFC'mustfbe ren-j` deredinoperativeduring the portion of the tuning operation just priorto the tuningcondenser setting atQWhichl the desiredfsignal Would be ob-v l, `rtained'with' the AFC in inoperative condition-e30 When, howeventhevariable'condenser has been adjusted within the channel of the desiredstation;V the AFC is again .rendered operative and i completes 4thetuning operation. Such a corref" lation ofAFC operation'and `tuningadjustmenta not' only` results in aycomplete simplication of the tuningoperation, and accuracy of station selec'ting, but further gives rise toquie tuning.

between adjacent signal channels Where auto- It may, therefore, vloestated that it' is another important objectof my present invention topro- 'vide in a superheterodynereceiver equipped with, .o

AFC and a station selector dial mechanism which is rmechanicallycoupledwith the .tuning con-:A5`

denser device, a control switch located at a xed reference point withrespect to the selector dial,

and` which functions toi render inoperative the f AFC during arelativelysmall portion ofl the dial `rotation in order to eliminate`the tendency ofmio the AFC to cause a shift inthe local oscillator ovfrequency to an extent that one carrier Will cause response to the`exclusion of other carriers.

Still another object offrny present invention is o to provide asimplified and accurate station se-$55.

lector device for a radio receiver of the superheterodyne type, andwhich receiver is equipped with AFC of the local oscillator; the stationselector generically comprising a rotatable dial provided with a seriesof spaced openings; the openings corresponding to different desired-stations; and a shiftable-stop element being positioned in suchrelation with respect to the selector dial that the receiver tuningdevice has its motion of adjustment arrested at the same locationregardless of Whether the rotation of the dial is clockwise orcounter-clockwise.

Another object of this invention isV to provide a radio receiver of thesuperheterodyne type with an AFC network, as well as a station selectordial for simply and accurately adjusting the tuning condensers of thereceiver; the dial being provided with adjustable spaced station buttonsprovided with elements adapted to mechanically co operate with a dialrotation stop member in order to limit the rotation of the Vdial inaccordance` with selected station buttons; and the selector dial beingfurther associated with a control mem- ;ber for the AFC network with theresult that the AFC isoperative at all times except when a selectedbutton is adjusted into mechanical cov'operation with the stopmechanism.

And stillj other objects of my present'invention are to improvegenerally, the simplicity, accuracy trol mechanism, and more especiallyto provide such mechanisms in superheterodyne receivers las acteristicof my invention are set forth in particy ularity in the appended claims,thevinvention, it-

lself, however, as to both its organization and method of operation willbest be understood by reference to the following .descriptionctaken in`connection with the drawings, in which I have in- I dicated variousmechanical embodiments whereby my invention maybe carried-into effect..

Fig. 2 is a front view `of the station selector :mechanism, of the typeshown in Fig. Las* viewed from the front of the radio receiver operatinglpanel, v

Fig. 3 is a partial sectional view of the-'station selector mechanism,taken along line 3 3 of Fig.

2 looking in the direction of the arrows,

vdetailed construction of the modication of 1Fig.6,

Fig. i8 is an 4end view'ofthe selector modification in Fig. 6,

Fig. '9 isafront viewof still another modified formvof selectormechanism,

Fig. 10 is an end view,A partly in section, of the selector'modicationof Fig. 9,v

11 is vanother modification, Vviewed from V-Vthe receiver panel, of theytype of selector Vrnechyanism yshown in Fig. `9, Y

lFig. 1'2-*i-s an' end view, partly in-section, of the modificationvshown in Fig. l1.

`specific AFC network employed therewith, it is believed suflicient forthe purposes of this application to point out a typical receiving systemwhich can be utilized in conjunction with the ncvelstation selectormechanism of my present invention. The receiving system shown in Fig. 1is a conventional representation of the system shown in detail in Fig. 4of application Serial No. 45,413, filed October 17, 1935 by S. W.Seeley, patented June 21, 1938 as U. S. P. 2,121,103.

Itl will be suicient vfor those skilled in the art, to brieiiy describethe main elements of such a s supe'rheterodyne receiving system which,is provided with AFC. The usual signal carrier energy collector A, suchas a grounded antenna; a radio frequency distribution line; or theconventional collector used on an automobile radio receiver; is coupledto the tunable input lcircuit of :Le receiver. The tunable input circuitusual`y comprises a variable tuning condenser I, and it is to be clearlyunderstood that the first stage of the receiver may be a radio frequencyamplier. In order to kpreservesimplicity of disclosure and drawing, `thenumeral 2 designates the rst detector.v e

The output circuit 3A of the iirst detector is resona-ted to theoperating intermediate frequ'ency. which may have a value, for example.ofy 'to465 k. c. (kilocycles). .The I. F. am-

, plifier has its inputcircuit 5 resonated to they operating I. F. andcoupled to the first detector output circuit 3. The I. F. amplifier Itis followed by ai double diode tube, as in the 6H6 type tube.

This type of tube is provided with independenty diode electrodes, andthe common resonant input circuit l' has one side thereof 'connected tothe diode anode 8. while the opposite side of the circuit is connectedto the diode anode 9. The

uhigh alternating potential side of the output circuit 6 of the I. F.ampliiier Il is connected through condenser til to the midpoint of thecoil 'l' of input circuit l. This midpoint i l is connected to thejunction. of resistor portions l2 and I3; one side of resistor i? beingconnected to the cathode B of the diode ii-SZ and one side of resistorI3 being connected tothe cathode 9' of the diode 9 9.

The condenser i4 is connected between cath @des 8 and 9', and thecathode 9 is grounded.`

The input circuit I is tuned to the operating I. F is reactively coupledto ythe circuit E. as designated by the reference letter M. The audiocomponent of detected I. F. energy is impressed upon one or more audioamplifier stages, followed by a reproducer. through lead I5 andcondenser I6. the latter being connected to the junction of resistors l2and i3. The automatic volume control (AVC) connection i? is employed toapply the direct current voltage component of rectified yI. F. energy tothe signal grids of controlled tubes and 1i. The AVC connection il ismade tothe junction of resistors l2 and i3, and of course, the

, directcurrent voltage component is transmitted through appropriatelter resistors before being' applied to the gain control grids of thecontrolled tubes. ,I

The AFC network involves the tunable tank circuit I8 of the localoscillator I9. As is well known the variable lcondenser 2Il in the tankcircuit `I8 has` its rotors mechanically uni-con trolled with therotorsof the variable tuning condensersj of the tunable signal circuitsfeeding the rst detector.` The'dottedline 2I represents such mechanicaluni-control.. Of course,4 the oscillator I9 is tuned, at any` settingofthe tun-l is varied' through the operating frequency range,

which may be the broadcast bandl of 500 to 1500 k. c. C l

The locallyproducedoscillations are impressed `on the first detector 2in any desired manner, as

by impressing them on vthe cathode circuit of the rst detector;Ofcourse, itis not essential to this invention to employ7 separate tubes2 and I9 for the mixer and oscillator functions. 'A penta- `gridconverter of the 2A7 type may be employed, `in any well known manner,`for a composite oscillator-mixer stage.` In any case `there iselectrically associated `with the tank circuit I8 a frequency controltube 22. Theconnections between I the plate circuitof tube 22 and tankcircuit. I8

are such that a negative across the tank circuit.

Briefly, and without going into capacity is reiiected `a detailed `dis-.cussionof the specific connections between the frequency control 22 andthe tank circuit I8, it is pointed out that a resistor 23 and condenser24 are connected in series across the tank circuit I8.` If theresistance of resistor `2?- is large compared to the" reactance` ofcondenser 24, currents through this series circuit will besubstantially' in l phase with the voltage across the tank circuit I8. lThe current passing through the condenser 24 produces avoltage acrossthe condenser which lags the voltage across the tank circuit bysubstantially 90. `This lagging voltagek is applied to the grid ofcontrol tube 22, and the latter` is preferably of the high mu,high plateimpedance' type. AItcan then be seen that the plate current, flowing inconnection 25 to tube 22 will be substantially 90 ahead of the voltageacross the tank circuit I8. The current through the tuning condenser ofthe tank circuit I8 lags thevoltage across that 4circuit about 90. Thus,any plate current fiowing through' connection 25 to tube 22 actsasthough the current owing in the variable tuning condenser has beendecreased.

The AFC connection 26 is madev from the control" grid of tube 22,through an appropriate filter resistor, tothe cathode sideofresistor I2..The mutual conductance of tube 22 isvaried inde `pendence upon themagnitude of the direct current component of the differential rectifiedI. F. energy. The magnitude and polarity of the po tential at thecathodeside of resistor I2 vdeter` lresonant frequency is applied, areadded vecl torially, the absolute magnitude of the resultant ondarycircuits I5` and] are so related that two vector sum. potentials of thevprimary and sec- 5 'ondary voltages may be realized. The magnitude andthe polarity ofthe potential at point 4I) determines the magnitude ofthe effective inductance reected across tank circuit I8. Thus,l if the`AFC voltage applied to the grid of` tube 22 is positive (therebyovercoming some of the `initial bias appliedin the cathode circuit ofthat tube), its mutual conductance is increased. The amount of leadingcurrent flowing in connection 25 is thereby increased; which is thesame'asl through the lagging current flowing throughthe variable tuningcondenser 20 has been decreased. This, in turn, acts asthough thatcondenser had been decreased .in value `thereby `causing" the tunedfrequency of tank circuit I8 to increaseA Assume, now, that `a signalimpressed on primary circuit is approaching the I. F. value of `465 k.c., an operating frequency chosen by way of illustratiom but is lessthan the latter; and also assume that point has a positivepotentialwithrespect to ground. Then Vthe frequency departure may be due to a shiftin oscillator frequency towards a lower frequency,l or due to tuning thereceiver towards the high endof the tuning range. The grid of tube 22becomes positive, and increases` the gain of the tube. This willresult'in an increase in the effective inductance reiiected across tankcircuit I8;v and the p frequency of the tank circuit will increase.` Inthis way the frequency difference between the signal and oscillatorcircuits automatically is made to increasetowards the desired I; F.value.

A practical difculty encountered in employ- Aing AFC' in `asuperheterodyne receiver is -the kproblem of dislodging a strong signalto make i way for a weaker one on a closely adjacent channel, withouthaving the weaker station jump right across the "band toV disappearonthe other side. To overcome this diiculty a switch 3D may be employed.l

'I'he switch S0 functions to ground the bias voltage derived frompoint40, and rendersthe AFC network inoperative at the will of theopierator.r This offers a means for correlating the 4operation of theAFC network with the tuning 50 operation so as to render the tuning ofthe receivingl system not' only accurate, 'but highly simplified. `InFig; 1 there is shown schematiiliary switch 3l which comprises arelatively fixed contact element 32. and a relatively movable contactelement `33. The contact 32 is connected by lead 34to the AFC line 26,whereas the `con-` 30 may be mounted in the rear of the receiver`chassis, whereas thesupplementary switch kEll maybe mechanicallyassociated with the selector dial as shown'in Fig. 3. 1 y y The stationselector mechanism that is em-f5 l ployed is of the dial type. Itgenerally, comprises a rotatable disc 4H which is provided with aplurality of station selector elements, or ears, 4I.r Each of theseyelements 4I is provided atits outer en@ with sdepressibie button`4in/and ati-f7.0 its inner end with 'a threaded screw member 43. Thefunction of members 43 is to adjust each of the selector elementslll`inany desired radial' position `alongfthe periphery of the dial disc40. vA groove 44 in thel exposed face of thedal disc `.7.5

yjusting screws 43. This Apermits the elements '4l 'tobe adjusted-todifferent points along the .periphery of disc 40. Upon depression of abut- -ton 42, a pin 45 is projected tothe rear of the ndisc ="40.\ Theyprojected pin 45 has a path of :revolution such that it comes incontact With the endtoffa pivoted switch closure member 46, the

latter being limited in pivotable motion between a pair of stops 4l. Theupper end of switch closure member 46 is provided with a widened edge,

.one point of which is capable of lmoving the con- :tact element331intocircuit oli position when :theipin'45 is moved into abutting positionagainst VAthefm'ember 4E.

`When the disc `lll is rotated lin one direction :the .pin`45 associatedwith a particular depressed 40 vwith its plurality of carrier members4l.

't'button "42 willmove the closure member 46 in 'the 'direction ofrotation 'of the disc.

When the latter is rotated in the opposite sense, then a -pin v45 willmove the member 46 in the opposite .direction.

However, regardless ofthe sense of rotation of disc'40, the pin 45, whenshifted into through any desired mechanical coupling arrangement. Forexample, a 2 to l reduction =gear ratio is shown employed to'mechanically .couple the tuning device 2l tothe rotatable disc 14u.,'Ihis reduction gearing comprises a small vdrive gear '46 which isrotated in unison with vdisc 4D; the driven gear 41 meshing with gear46,'and in turn having a rigid connection to the tuning velement 2l.

ingeneral, therefore, it Will be seen that the -manually adjustabletuning device of the receivfing system comprises Aa rotatable stationselector vvdisc Vprovided with a plurality of independent stationselecting buttons 42.

The tuning process .involves the insertion of the users finger in theborehousing a button 42, assuming the button has been depressed, and therotation of the dial The rotation ceases when the particular pin 45moves into contact with the pivotable closure member y4t, and the lattermoves into contact with one .of-the stop pins 4l. This results in therendering of inoperative at that point, as well .as Aa positivearresting of the rotation of dial 40. The button 42 is releasedtherebywithdrawing pin 45, and opening switch 3l.

, The constructional details of the selector dial and its plurality ofbutton carrier members will now .be considered. Particular attention isdirected to Figs. 2 to 5 inclusive for these constructional details. InFig. 2 there is shown the appearance of the station selector mechanismwhen viewed from the front of the operating .panel of a radio receiver.The disc 40 is provided, concentrically therewith, with an annular Adialbearing scale indicia l which denote the variousfrequencies to bereceived. Where the receiveris of the multi-range type, this circulardial 50 will bear-a plurality of scale ranges to correspond tothedifferent frequency bands of the receiver. The scale 5!) is rigidlysecured to theouter face of disc 4l) in any desired manner; rotation ofthe disc k4l) therefore also resulting 'in rotation of the dial 50. f

=Each of the button carrier members 4I is bifurcated at the point ofcontact with the periph- -ery of disc 40. .As shown in Fig. 3 in greaterswitch 3l.

eisfproviuedffor Cooperation-,With-the ends ofxad- "detail, each ofthemembers 4I is rigidlysecured to a predetermined position on theperiphery of disc by means of the threaded coupling between screw 43 andthe threaded bore provided in one of the legs 5l of the bifurcatedportion of each of members 4l. Each of screws 43 is provided with a balltip 52, the tip being shaped to complement the shape ofthe groove 44.'I'hat is to say, the cross section of groove 44 will be substantiallysemi-circular so as to receive snugly the semi-circular contour of theball tip 52. It will now be seen that a member 4I can be substantiallyrigidly secured to the periphery of disc 4H by the use of a screwdriver, which is employed to rotate the desired screw 43. The buttons 42are disposed within bores provided at the free ends of each carriermember 4 I.

As shown in Fig. 3 a button 42 comprises a shank Si! which is adapted toreciprocate through a narrow bore provided at the rear face of themember 4|. This rear bore widens into a second bore adapted to receive aspring 6| which normally maintains the head 62 of a button in a positionsuch that the exposed face of the head 52 is substantially in the sameplane with'theA lremainder of the Aexposed face of member 4I.

The head 32 of each button is arranged to reciprocate within a third and`wider bore 63. The head 62 may comprise, as shown in Fig. 3, acomparatively narrow recessed casing within which is disposed a circularstation designation plate 64y having its upper face in contact with atransparent protective circular plate 65. As shown in Fig. 2, the headof each button will, therefore, have exposed to the View of the set userthe various station call letters. Those shown in Fig. 2 represent' thevarious station call letters of broadcast stations encountered in theNew York City area.

The shank B of each button device 42 is providedy with a normallyprotruding pin 1D. 'Ihe portion Aof the pin "lll between shank 50 andthe rear tip of the pin is in threaded engagement with a nut il. Thelatter nut functions as a stop nut, and its face, in contact with therear face of ear 4l, limits the movement of pin 'l0 in the direction ofVthe operating panel. Upon "movement of the button head B2 in adirection to compress spring 5I it will'be seen that the pin 'lll ismoved into alignment with the path of movement of the double bell cranklever switch 415 which functions to close the AFC control Upon removingthe depressing force from the button head 62, the spring 6| pushes thehead 62 into `its normal position, and thus retracts the pin 'Hl fromthe path of the lever 4B.

The AFC switch 3l, asr shown in detail in Figs. 4 and 5, comprises thecontact elements 32 and 33. The element 32, as well as element 33, has

one end thereof positively gripped between insulaton spacers l2. Thecontact element 33 has spaced therefrom a presser strip 13, one end ofwhich is also gripped between insulation spacers. The bolts i4 functionto rigidly secure together the various `insulation spacers, and maintainthe ends of strips 32, 33 and 13 in spaced relation. The nxed ends ofContact elements s2 and 33 project beyond'the spacers T2, and numerals'l5 and i6 designate these projecting ends which act as connectingterminals to the lead 34 and ground. The free end of element 32 isprovided with a button Tl, and the free end ofcontact element 33 isprovided with a contact pin 78.

v y member 46, isvrigidlysecured toa support plate` 82, the latterbeing' spaced from the operating upper edge, the bolt 8l.

Since the strip 32 is in metallic `engagement with the` button511and'the'same is true of element 33 and its pin 18, contact betweenele` ments 11 and 18 results in a closing of the cir- 46 showing itsrelation totheswitch elements when it is moved into contact ,with pin41. The

.full line position of member 46 in Fig. 5 shows its relation to switch3l, whenthe depending portion 46'` is movedinto contact with stop 41'.

The upper edge 30 of ,member 46 `is movedlout of contact `with the undersurface of presser strip 13 whenever the depending portion 46 is swungtowards either of the stopsi41 or'41. `It will also be seenthatregardless of the direction of movement of the depending portion 46',the contact elements 32and y,33 will be brought into electricalassociation by the front and rear cam edges of the upper lportionofmember 46. Of course, the elements 32, 33and`13 are made of` flexiblemetallic strips` so that when the cam edges of edge Sillare moved lalongthe under face of strip 13, the kthree spaced strips willbe capable ofyielding in the direction in which they are urged. The bolt 8l, `whichacts asthe pivot point for panel 83 of the receiver. As shown inFig. 3,the frontpanel 83 of the receiver is provided vwith a metallicring 84.The disc 48 is disposed concentrically with respect to the ring 84, andas seen in Fig. 2, `the ring 84 `servesas anouter setting for the discand button carrier assembly. Itwill` be observed that there is asubstantial peripheral space between the periphery of the circle ofrevolution of the button carriers, and the inner circular edgeof ring84. The spaced plate 82 has secured to it, at a short distance from its'Ihe stops 41 and 41' are 'secured to the front face of plate 82, thestops being spaced from each other in the manner shown in Fig. 4. Thedepending portion 46of member 46 has its rear face in contact with thefront face of plate 82, so that when member 46 is shifted between thestops 41 and 41', its rear face is in sliding contact with the frontface of The plate 82 'is rigidly secured to the chassis of the receiverinany desired manner, and through the center thereof there is providedan aperture which acts as abearing for the shaft 85, which is integralwith the 'rotor condenser shaft 86.` The `gear 81 is secured `to the endof shaft 85 in any` conventional manner, and gear 81 meshes with drivinggear 8,8." The gear 88 is pinned to the in tegral hub 88 of disc 46. Thehub 88` is provided with a tubular extension 80, the latter extending tothe rear of hub 89, and through a second aperture in plate 82. Theextension and hub 89 is provided with af bore in which is disposed the,

horizontal portion Si of the fixed index arm 92. As clearlyshown in Fig.3, the index arm 92 is formed from a single element, the vertical eX-posed index arm 92 :being maintained in the same fixed position byvirtue of a downwardly directed Normally the upper edge i condenserelement of the radio receiver.

'through 180.

. bent portion 93, which is secured to the rear face of'plate 82 in anyconventional manner`-` The shaft 86 of the uni-controlled gangofcondensers` is .additionally coupled,` if desired, to a conventionalform of tuning knob94l As clearly shown 3, the tuning knob 94 may bepro-` vided inthe lowermost` portion of circular ring 84,

and in alignment with theindex arm 92. A shaft i 951s provided, whichmay be arranged parallel' tocondenser shaft 86,` and this shaft had anend thereof which has the knob 94 secured thereto. .The manuallyrotatable shaft 95 can be mechanically coupled to condenser shaft 86 inany conventional. fashion; a belt and pulley arrangement 86 being shownby vway of example. It is to be clearly understood,.however, that thetuning knob 94 and its associated mechanical coupling to condenser shaft86, may be entirely omitted; since it is only'necessary to use the`station selector dial 40; f i

The numeral 91 designates the variable tuning .not believed necessaryto`describe the construction of this element since those skilled in the artare fully awareof such construction. It is only believed necessary topoint out that the numeral 21` denotes the conventional gang of variablecon` densers corresponding tothe variable tuning con# densers 28 and IofFig. 1. It is also pointed out that gears 81 and'88 ofiFig. 3correspond respectively to gears 41 fand 46 ofFig. l. l It will now` be.seen that as abutton 42 is depressed, and the dial assembly 48'is`rotated, the condenservshaft 86 will be rotated by virtuev of thegearing 88--81. Since the index on-92 'is rigidly anchored with respectto the rotating dial face 50, there is supplied, in addition to thestation designations on the button faces, kilocycle designations to` de`note theposition. of condenser shaft 86 at any l K rection.` Duetotheconstruction of conventional variablel tuning `condensers, the`condenser` shaft 86 cannot becontinued in adjustment in the samevdirection after being `adjusted into complete meshing with the stators;neither can the rotor yshaft be continued in adjustment in the same-directionafter the rotors have been rotated completely out of mesh'withthe stators.

However, between these two'limting positions, `the rotor" shaft 86 canbe adjusted in clockwise or counterrclockwise sense. As iswell known,4this adjust-` ment between the` limitingpositions is `only it is desiredto initially calibratethe selector mechanism, orwhether` it is desiredto re-calibrate 4the selector mechanism when areceiver is moved from onebroadcast area into a relatively distant area,` it is only necessary torotate the Acondenser shaft 86 by moving the dial 40 `until a station isheard ywithout appreciable distortion. At that setting of the ,condensershaft 86a button carrier member r4I` isshifted along the periphery ofdial 40'until pin 10 contacts portion 46' of Henceaz to 1 reductionratio` gearing is used between shaft 8,6 and dial 40` tor secureadvantage of 360 on the dial 48.

is n

member 46, and moves the latter against one of the stops 4l or 4l. Atthat position of member 4I, .its screw 43 is tightened to fix member 4Ito the dial. 4D at the switch 3l closing position.

'I'his procedure may then be repeated for as many of the remainingcarrier members 4I as is desired. Of course, the calibration may beaccomplished by. employing the tuning knob 94, Where one is provided onthe receiver. If the receiver is of the multi-range type, and thestation selector dial l4I) .is used for the broadcast band exclusively,then it will be desirable to provide the tuning knob S4 for operation inthe shorter wave bands. As stated before, the entire 360 of the selectordial 40 is utilized by Virtue ofthe reduction. gearing 88-81; thispermits a wider distribution of members 4l on the selector dial.

The two members 3l and 46 definitely `assure reception of a desiredstation by causing the. AFC to be .rendered inoperative. This isaccomplished during the portion of thev tuning operation just prior tothe tuning condenser settingl at which the desired signal .would beobtained with the AFC in inoperative condition. When the variable.condenser rotation is such/that the condenser shaft 86 has adjusted therotors of con.- denser 91 to tune the oscillator and signal circuitswithin the channel of the desired station, then the AFC is againrendered operative and completes the tuning operation accurately.Considered in mechanical procedure, this electrical sequence of tuningsteps is accomplished in the following manner. v

Assuming that station WINS is being received, as shownin Fig. 2, and itis desired to tune the receiver to station WEAF; it is lonly necessaryto insert a finger into the carrier member 4I provided with the WEAFbutton. AThis is accomplished by pressing down on the WEAF button. Theentire selector dial assembly is then rotated in clockwise, orcounter-clockwise, direction depending on the position of the condenserrotors. `There will be no obstruction to the movement of the WINS buttonbecause its pin 10. is in retracted position. The projected pin 'I6 ofthe WEAF button will cause rotation of dial 4i! to cease as soon as thepin strikes the depending portion 46 of member 46, and causes portion 46to abut one of the stop pins 41 or 41. When the user of the set observesthat further movement.

of the dial 40 is impossible, then it is merely necessary to remove thefinger from the WEAF button. Removal of the pin 'l0 of the WEAF buttonpermits the member 46 to attain its position shown in Fig. 4, thusopening the switch, 3D and restoring operation of the AFC. When the AFCbecomes operative, it immediately functions to adjust the localoscillator frequency so as to accurately tune the receiver to WEAF. Itwill, therefore, be seen that the initial calibration of the selectordial need not be Very accurate. The action of the AFC is such that itwill automatically and accurately tune the receiver after the receiverhas been approximately tuned by adjustment manually of condenser shaft86.

v, Of course, the station indicia on each button 42 may be made ofAmaterial vwhich glows inthe dark, such materials being well known;thereby facilitating adjustment of the dial in the darkness, as in thecase of an automobile radio receiver employed in night driving. Again,the station indicia may be in braille so .that blind persons may`easilyy use the mechanism.V

The switch so, also comming the Arc net..

Work, may be used when it is desired to render the AFC inoperative for along period of time, and independently of the switch. 3l. Again, it isto be noted that while the resiliency of strips 1.3, 33 and 32 can berelied on to restore the member 46 to its normal position shown in Fig.4, it is obvious that the portion 46 may be designed to nor mally.maintain the member 46 in its median position. While the dial 40 canbepositioned on the operating panel above the tuning knob, tone controlknobandvolume control knob, it is within'the scope of my invention todispose the selector dialat the side of the cabinet for aestheticreasons. Again, if it is desired' to keep the selector dial on the frontpanel, and if for design purposes it is desired to keep the dialnormally hidden from view, a slidable, or pivotable, door may be usedto. cover the selector dial. From Fig. 2 it will. be seen that there isplenty of space between members 4.I on dial 40 to provide for recalibration when the receiver ismoved from one broadcasting area to anarea where entirely different stations are broadcasting.

It is believed that the electrical operation of the AFC, as the receiveris tuned, will be obvious from the aforegoing description. As soon asthe receiver is tuned Within a desired signal channel, the AFC willimmediately function to adjust the oscillatorfrequency so as to produceI. F. energy substantially equal to the operating I. F. Because of.thisfunctioning of the AFC network, an additional .advantage is securedby virtue of the selector dial construction. Since the receiver isequipped with an AVC network it functions to reduce the sensitivity ofthe signal selector circuits as long as'signal energy is `applied to theAVC rectifier.

Since the .AFC network is operative at all times in a receiving systemembodying the present invention,. it necessarilyfollows that signalenergy will be impressed on. the AVC rectifier at all times. In otherwords, vthe AVC connection Il in Fig. 1 is .practically functioning atall times to reduce the sensitivity of the signal stages preceding. theI. F. network. This is particularly true when tuning from one stationposition of the selector dial 4!) to another position. Whereas in aconventional radio receiver equipped with AVC, inter-station adjustmentci. the receiver results in much noise; the present receiving system andits station selector mechanism produces quiet tuning between channels..Further, it will be seen that this is accomplished without the use ofany auxiliary, and well known types of, noise suppressor networks.In-other words, the AFC network not only :functions to render the tuningoperation simple and accurate; but it also cooperates with the AVCnetwork to provide quiet interchannel operation.

A modiiication of the selector mechanism is illustrated in Fig. 6. Thislatter figure shows the appearance of the selector mechanism as viewedfrom the operating panel. It will be seen that it comprises a disc Illprovided on its outer face with a plurality ci spaced tubular devices IFHI The outer face of disc HBO is also provided with a concentric scaledisc 102, a stationary scale arm IIlS depending from the rear of theoperating panel IM, and cooperating with the indicia IUS provided on thedisc 162. In Fie'. 7 there is shown in detail the manner of constructingone of the tubular finger positioning devices IUI. It willbeobservedthat each of the devices IUI comprises a cylindrical casing HIB having abase i which grips the peripheral edge of disc |60. Each of casings I|56 is provided with a rounded periphery at the exposed opening Ii, anda false bot-` torn discI I Iis provided at an intermediate point alongthe length of casing 06. The disc III pears on its outer face stationindicia,and the latter areclearly shown in Fig. 6. The `disc |00 isdirectly coupled to the condensershaft H2. The numeral H3 designates, inFig. 8, the gang of-v condensers, and itv will be observed that therotor shaft H2 is directly coupled to the disc |00 by any well knownform of mechanical coupling H4. In view of this construction the finger`positioning devices II can only be arranged along 180 of the exposedface of disc |00; this follows 't from the fact that the rotors of thevariable conbottom of a 'support plate H1, the latter beingA spacedfrom, and positioned rearwardly of,` the disc Hill." The circuit closingend of contactor H4 is resiliently secured to a bracket Hi8 whichdepends from the lug H5.` This is. accomplished by securing spring H9between the'free end of bracketIlS and the contacting end of the con-40y tactor H4.

The' spring-retained end oi. contactor H4 is provided withopposed'contact points |20 and j |2I; and thesepoints are arranged tocooperate with contacts and |2I respectively. .lattertwo contacts areconnected in common, and are provided with a single connection to theAFC network. The ground connection is provdedl'to thefcontactor H4, anda pair of stops |22 and |23 'are provided on either `side of thecontactor H4 in order tolinnt the arcuate motion thereof. 'Ihe upper endofthe contacter I4 is providedwith a configuration as shown in Fig. `6,and it will be observed that this conguration generally comprises a pairof opposed t concave arcs. The lpurpose of this conguration is to adaptthe upper opposed edges of the free endof contactor IUI-to the-contourofa'inger ypositioned ina device IOI.

Itlwill now be seen that a finger, disposed in fafgiven'icylind'er IIlI,shifts the contactor H4 into AFC circuit closing position when thefinger contacts the upper edge of the contactor and rotation of vdisc Imi is continued.' As shown inY Fig.V 6, and assuming that WABC isdesiredfor reception, it will be seen that the finger of the user will shiftthe contactor H4 into the dotted line position H4'. In this position,the stop |23 limits further motion of the contactor, and causeselectrical contact between point` |2Il and contact I2I.` In thisposition, the AFC network is in` operative,and normal tuning ispermitted. As

i soonas the iinger of the user is removed from theWABC cylinder, thespring H9 retracts the contactor I I4 into normal position, and the AFCnetwork is operative to accurately tunethe receiver.` n

In designingvthe stop device for the selector dial, whether itbe for theform shown in Fig. 3, or the formshown in Fig. 6, it is necessary tohave the pivotable switch closure member shifting in accordance with thedirection of `rotation of the selector dial.` `This assures `the tuningmeans coming to rest in the same location regardless of whether thedirection of rotation is` clockwise or counter-clockwise. Mechanically,this action is secured by permitting the toggle member to be displacedfrom its normal, `orcenter, position a distance equal to the radiusofthe toggle actuating means; in Fig. 3this actuating means is a pinprojected by a depressed button.` Here, the abovementioned radiusuis theradius of the button pin. In `the iinger-'actuatedmodication, thisradius is that of the finger-positioning aperture. l

The selector mechanism is shown in still' further simplified form inFigs. 9 and 10. In, this arrangement, the selector mechanism comprises adisc having a bore |3I, the bore receiving `therotor shaft |32 ofthe'gang of"condensers.

In other words, the disc |3Ufis directly coupled` to the rotorshaft. vAsemi-circular slot |33 is pro vided in the body of disc |30, thusproviding a rear segment |34 and a front segment |35. j Thefront, orselector, segment |35 is provided witha plurality of spaced openings|36, and `the;inner -iace of the rear segment |34 isuprovided with astation designation disc |31. The' station indicia.

|31' are provided adjacent the peripheral edge.

of plate I3i; the indicia being providedat points such that they canbeviewed thro-ugh theirA cor-1` `responding selector openings |36. fAsshown in Fig. 9, each opening |36 will thensurround ar correspondingstation designation |31".`

Of course, the diameter of` each opening |36` should besuch thatthefmger size of the average understood that the AFC switch constructioninl l lconnection with Figs. 6, 'I and 8 is tobeemployed iny connectionYwith this `selector modication. The association of the form shown inFig. 9 with an AFC switch is not shownY because it is beappreciatethemanner of" this mechanical asso ciaton from Figs. 6,7 and4 8. u

`It will be iobservedthat in the last two modifications described, thestation selectordevices are` limited to an 180 distribution .along theperiph-V ery of the station selector disc. The entire, circumference ofthe selector rdisc may. be used by providing an additional AFC switchdiametrically opposite to that shown `in Figf. I This form Aof selectormechanismis shown `in Figs. 11 and 12. The selector disc andnger posi`tioning devices are similar in construction to the form shown in Figs. 9and 10. 4Thatis to say, the numeral|40 designates a selectordisc-,provided with spaced iinger vpositioning openings. I4|

tion` |42 is provided withthe station indicia disc through the differentopenings |4| One AFC switch is located lowermost point of disc |40, anda second' AFC switch I5I is positioned` diametrically opposite `lievedthat those skilled in the artwillreadi1y sos. f

con

adjacent thev y 7oz'- switch |50. It is to be clearly understood that lboth these `switches are constructedas shownjin Figs. 6. and 8.* Forthis reason, these switches are schematically.r represented yin Figsuiland l2.`

' 35ian. angular: distance greater than 180.

The common connection to groundv from the contactors of switches 150 andISI is shown in' Fig. 11and.. the latter additionally shows the commonconnections from the pairs of contacts of each of switches l5@ and ii to.the AFC network. f

In this way, it is possible to use either of the modiiications shown inFigs. 8 and 9, and yet have a Wider distribution of linger positioningde- 10 vices along the periphery of the selector disc. This canbe easilyseen from the iact that since the rotors of the variable condenser, towhich shaft l32in Fig. l2 is connected, have a maximum rotation of,180", it is only necessary to position 151 half `the stations on halfthe disc Mld, and the other half of the stations along the periphery ofthe other half oi the disc. Because of this arrangement, and theprovision of a pair of switches I5!)v and 85|, regardless of theposition of the ro- W3 tors of the variable condenser, the maximumrotation of disc Mii will not exceed 1809.

It is thereby possible to have the spacing between lnger positionopenings Uil much wider than in the modifications of Figs-6 and 9'; fur-25:3 ther, the advantage over the modiiication shown inllfigl.l 1resides in the fact that no mechanical gearing isemployed between theselector mechanism and the rotor shaft |32 and yet the full 360 of. thesel-ector'disc is taken advantage of. An 301; additional advantage ofthe modification shown in Figs. 11 and l2 overthat shownin Fig. lresides in the fact that to adjust thejrotor shaft i325 .to anydesiredstation setting from any last.

' settngthe disc M0 need not be adjusted through In order to distinguishthe stations on half of the disc ma fromthestanonson the other half, adifferential, coloring can be employed on the station indicia.

While I have indicated and described several constructions for carryingmy invention into efiect, it will be apparentto oneskilled in the artthat myinvention is by'no means limited to the particular constructionsshown yand described, 45t but that many modifications may be madewithout` departing from the scope of my invention, as set-forth inthe'appended claims,

What I vclaim is:

'-ll In-combination with the adjustable tuning 505'? device of a radioreceiver, supplemental means for tuning the receiver, a device forcontrolling the operation of the supplemental means, a rotatablestation-selector discv arranged to vary said tuning device to differentstation reception-posilietionsa plurality of independent fingerpositioning devices mechanically associated with said disc, and means,relatively xed with respect to said rotatable disc, for stopping therotation of said disc, and actuating said control device upon 6055'adjustment of a selectedone of said devices to a iixed reference point.

2. In combination with the adjustable tuning device of a radio receiver,a supplemental tuning device, a rotatable station selector disc arranged"gto vary said tuning device to different station reception positions, aplurality of independent finger positioning devices mechanicallyassociated with said disc, and means, relatively fixed 1 70,with respectto said rotatable disc for stopping the rotationnof' said disc uponadjustment of a selected *one of said devices to a xed reference point,said stopping means comprising an element. arranged to rock between apair of stop u; members andmeansrcooperating with the element at itsrocking limits to control said supplemental device.

3. In combination with the adjustable tuning device of a radio receiver,a supplemental tuning device, a rotatable station selector disc arrangedIiI to vary said tuning device to different station reception positions,a plurality of independent fin-ger positioning devices mechanicallyassociated with said disc, and means, relatively iixed with respect tosaid rotatable disc for stopping 10 the rotation of said disc uponadjustment of a selected one of said devices to a fixed reference point,said stopping means including a member arranged to rock between a pairof limiting points, means cooperating with said member at 15.- itsrocking limits to control said supplemental device, and meansmechanically associated with each of said independent devices for'rocking said member.

4. In combination with the adjustable tuning f device of a radioreceiver, a supplemental tuning device, a rotatable station selectordisc arranged to rvary said tuning device to diierent station receptionpositions, a plurality of independent finger positioning devicesmechanically `asso- I ciated with said disc, and means, relativelyfixedV `with respect to said rotatable disc for stopping the rotation ofsaid disc upon adjustment of a selected one of said devices to a iixedreference point, said stopping means being constructed and 3 0 arrangedto shift between a pair of limiting posi- `tio-ns in accordance with thedirection of rotation of said disc andv means cooperating withv saidstopping means at its shifting limits to control said supplementaldevice.

5. In combination with the adjustable tuning device of a radio receiver,a line tuning mechanism, a rotatable station selector disc arranged tovary said tuning device to different station reception positions, meanscontrolling the effect 40. of said mechanism, a plurality of-independent finger positioning devices mechanically associated withsaid disc, and means, relatively iixed with respect to said rotatabledisc for stopping the rotation of said disc upon adjustment of aselected one of said devices to a fixed reference point, each of saidpositioning devices comprising a depressible button carrier member, andeach depressible button being provided with a pin adapted to contactsaid stoppingmeansv to actu- 50, ate said controlling means.

6. In combination with the adjustable tuning device of a radio receiver,a rotatable station selector disc arranged'to vary said tuning device todifferent station reception positions, a plurality of independent ringerpositioning devices mechanically associated with said disc, each of saiddevices comprising a member provided with a bore, a spring-biased buttonmeans in each bore, and means, relatively fixed with respect` to said60,' rotatable disc for stopping the rotation of said disc uponadjustment of a selected one of said devices to a fixed reference point,each of said independent devices including means for adjusting a deviceto any desired position on the disc u for calibration thereof, a pincarried by each of said button means, and each button means beingresponsive to pressure of a linger for projecting a pin from apositioning device in such a manner that a pin comes in contact with thestopping 70.1 means.

'7. In combination with the adjustable tuning device of a'radioreceiver, a signal-responsive control circuit, a rotatable stationselector disc arranged to vary said-tuningdevice to different :4

and means, relatively fixed with respect to said station yreceptionpositions, a plurality of independent linger positioning deviceslmechanically associated With said disc, and means, relatively fixed withrespect to said rotatabledisc for stopping the rotation of said discupon adjustment of a selectedone of said devices to a xed referencepoint, each of said positioning devices being provided with a bore toreceive the nger of the user, and said stopping means including ashiftable element adapted to be` adjusted between a pair of limitingpositions, said shiftable element being included in a switch device forcontrolling the operation of said control circuit, andthe path ofrotation of said disc being suchthat the said usersnger comes intocontact with said shiftable element. l

8. In combination with the adjustable tuning device of a'radio receiver,a ne tuning device, means for controlling the operation of the latter, arotatable station selector disc arranged to vary said tuning device todifferent station reception positions, said disc being provided` with aplurality of independent finger positioning devices,

rotatable disc, for stopping the rotation of said disc and actuatingsaid controlling means upon adjustment-of a selected one of said devicesto a fixed reference point corresponding to the position of saidstopping means. l y 9. In combination with the adjustable tuning deviceof a radio receiver, a supplemental tuning device, a rotatable stationselector disc arranged to vary said tuning device toy different stationreception positions, said disc being provided with a plurality ofindependent finger positioning devices, 4and means, relatively fixedwith respect said disc vupon adjustment of a selected one of saiddevices to a fixed reference point corresponding to the position of saidstopping means, each of said finger positioning devices comprising anaperture provided in the disc and `saidstopping means comprising anadjustable element constructed andarranged to be rocked between a pairof limiting positions and means cooperating with the` element at itsrocking limits to control said supplemental device.

10. In combination with the adjustable tuning device of avradioreceiver, a circuit for controlling signal reception, a rotatablestation selector disc arranged to vary said tuning device to dierentstation reception positions, said disc being provided with `a pluralityof independent finger positioning4 devices, and means, relatively fixedwith respect to vsaid rotatable disc Vfor stopping the rotation of saiddisc upon adjustment of a selected "one of said devices to a fixed Ireference point corresponding to the position of said stopping means,said stopping means being included as a control switch insaidcontrolling circuit, and an additional stopping means arranged adjacentsaid disc` at a point diametrically opposite the yposition of the firststopping'` Vsuperheterodyne type, automatic frequency control means,responsive to received signal energy,

for .adjusting the local oscillator frequency to a` magnitude such thatthe vfrequency of the in- "termediate frequency energy is made toapproach an voperating frequency value, a mechanism for rendering theirequricy control inoperative, A'an adjustable station selectorconstructed and varranged to vary the` position of the adjustable tuningdevice of the receiver, said selector beine" respect to said selectorthat the-mechanism is actuated when a positioning-' device isadjustetoapredetermined reference point. f l2. In combination with a radioreceiver of th superheterodyne type, automatic frequency control means,responsive to received `signal energy,

for adjusting the local oscillator frequency to `a magnitude such thatthe frequency` of the intermediate frequency energy is made to approachy an operating frequency value, switch means for 'ngerpositioningdevices for adjusting `the selector to different desired stationsettings, and

said switch means being positioned in the path of movement of saiddevicesin such aimarinerI that the switch is actuated when a device isadjusted to apredetermined' reference pointgand additional means for1renderingsaid switch inactivev to affect the frequency control uponremoval ofthe finger from the` selected device. -i i 13. In combination`with'a radio receiver of the superheterodyne type, automatic frequencycontrol means, responsiveA to received signal Veriy c ergy, foradjusting the local oscillator` frequency to said rotatable disc forstopping the rotation ofv to a magnitude such thatthe frequency of theintermediate frequency energy is made to appreach an` operatingVfrequency va1ueswitch means for rendering thelfrcquency` control`inoperative, an adjustable station selector constructed and arrangedto` vary the position of theadjustable device of the receiver,

said selector being provided with a plurality of independent` fingerpositioningdevices for adjusting. the selector toi different desiredstation settings, and said switchmeans being mechani-` callyassociatedwith said devices in such a mari-fv the superheterodyne type,vautomatic frequency control means, responsive to received signalenergy,for adjusting the` local oscillator frequency to a magnitude such` that`the frequency ofthe intermediate frequency `energy ismadeitoapproachfan operating frequency value, switch means forrenderingvthe frequency control'inoperative, an'adjustable stationselector constructedand arranged tovary the position of.

the adjustable tuning device ofthe receiver, said selector beingprovidedwith a plurality of independent fingerpcsitioning devices for adjustingthe selectorto different desired station settings,`

and said switch means being mechanicallycy as-Y sociated with saiddevices in such a manner that the switch is actuated when a device isadjusted toa predetermined reference point, an adjust-1 ableelementadapted *to bevaried in` position switchmeans at each of saidlimiting pointajsaid adjustable. element being mechanically associatedwith said independent devices in such a manner that the adjustableelement is actuated forrectifying the intermediatefrequency energy and alocal oscillator adapted to impress locally produced oscillations uponsaid rst detector, an adjustable -tuning device electrically associatedwith said first detector and oscillator,y means, responsive to.r avariation of frequency of said intermediate frequency energy from theoperating frequency, for adjusting the oscillator frequency in a senseto cause said intermediate frequency energy to approach said operatingfrequency, a switch device for controlling the operation of saidoscillator frequency control means, means for varying said adjustabletuning device to i predetermined positions, and additional means foractuating said switch device to render the frequency control meansinoperative solelyv atsaidpredetermined adjusted positions-of the weinedevice- A176. In` a superheterodyne receiver provided With-at least afirst detector adapted to produce intermediateA frequency energy of apredetermined operating intermediate frequency, means for rectifying theintermediate frequency energy and-alocaloscillator adapted to impresslocally produced oscillations upon said first detector, an adjustableytuning device electrically associated withsaid first detector andoscillator, means, responsive toa variation of frequency of saidintermediate frequency energyfrom the. operating frequency, foradjusting the oscillator frequency inta sense-to cause said intermediatefrequency energyto approachsaid operating frequency,.a switchdevice forcontrolling the operation vof saidoscillator frequency control means,means for varyingsaid adjustable tuning device topredeterminedpositions,and additional means for actuating said switch device to render thefrequency -control means inoperative solely at said predeterminedadjusted positions of the tuning, device, signal amplification reductionmeans, responsive to rectified intermediate frequency energy,forautomatically maintaining the signal amplitude substantiallyuniformat the said rectifier when thev received signalamplitudeincreases, and said frequency control means acting to cause saidintermediate frequency energy tdbe supplied to said signal-rectifierbetween said tuning. device-.positions'whereby the tuning operationbetween said positions is quiet.

. 17. In a radio receiver of the type comprisingy amain tuning deviceand a supplemental signalactuated tuningmechanism for securing accuratetuning at selected station positions of the main device, means forcontrolling the operation of the .supplemental mechanism, an adjustablestation selector constructed and arranged 'to adjust said main deviceto'selected positions, said selector. being provided with a plurality ofindependentstation representation devices for positioning ,an indexelement, and means constructed and arranged simultaneously to stop theadjustmentxof said selector upon adjustment 'of the positioned ,indexelement to a fixed reference pointcorrespondingpto the .position of saidstop.-

Lping means, and to-.actuate said control'means...

t 118:11; a-t'radio, receiver-of the type provided withfaflstationselecting circuit including a main tuningelement, an automatic tuningcontrol arrangement for insuring accurate tuning of the receiver atselected positions of the.` main element, means for rendering saidautomatic control ineffective, and additional means, responsive toadjustment of said main tuning element, for actu-l ating saidlast meansat said selected positions.

1,9.,Selective adjusting mechanism for tuning radioh-receiversAembodying an automatic frequency control circuit comprising a manuallyshiftable element drivingly connected with a tunable element of saidreceiver and selectively operable means for` stopping the means of theVshiftable element when the same and'said tunable element reach adesired tuned position, and means operatively associated with said stopmeans for grounding said automatic frequencycontrol circuit momentarilyas said desired tuned posi-tion is reached.

20. Selective adjusting mechanism comprising rotatable means including aportion formed with a series of openings adapted to receive the fingerof anoperator-when turning the rotatable means,y stopgrneans for eachopening including a button portionA extending in an opening anddepressible therein bythe. linger of the' operator, said stopmeans beingnormally'inactive but being adapted upon depressionr of thecorresponding button in its, openingv to stop rotation of the rotatablemeans-whenthesame reaches an adjusted position determinedfby said stop.

21. Selective.k adjusting mechanism comprising amanually 'shiftableelement and selective means operable during and as a part ofthe shiftingof saidi'elementr to stop the same when. a desired adjusted position isreached, said selective means comprising-av plurality .of `selectorsindividually andE selectively depressible on said manuallyshiftableelement, each depressible selector comprising Vabutton. member'andl a stem-like stop elementi aXially.-y movable onthe manuallyshiftablel element, resilient means arranged in contact withsaid-'button Vmember and applying pressure L.-

directly :thereto thereby normally urging-3 said stop element towardinactive position on the shiftable element, and means forming acooperatingy stop. adaptedl to engage said stopfelement when theselector is depressed on said shiftable element whereby to stop theshiftable-element in a position determined by said stop element.

22.'.Selective adjusting mechanism comprising rotatable means includinga portion formed'with openings whereby said means may be grasped inturning the same, means extending in said openings and forming stopsselectively operable in eifectingturning movement to check'said movementwhen said rotatable means reaches a desired adjusted position determinedby the selected stop;

v23. In combination with the adjustable tuning condenser ofa radioreceiver, a rotatable station selector member arranged to actuate saidcondenser; to different station reception positions, ai. plurality ofselectively operable pushbuttons` mechanically associated with saidselec.- tormember,z means relatively-fixed with respect to saidrotatable selector member for stopping the: rotation of said member uponadjustmentof afselectedione of said push-buttons to a xed referencepoint, a control circuit included in said receiverand `havinga normallyopen switch, and Ameanscontrolled by .said push-buttons at their limitsof .travel for actuating the switch to lclosed position.; l

l 24. In combination, an adjustable tuning condenser of a radioreceiver, a rotatable station selector member arranged' to adjust saidcondenser to different station reception positions, a plurality ofselectively operable push-buttons carried by said selector member andcapable of sliding movement in a direction normal to the direction ofrotation of the selector member, a stop pin carried by each push-button,means co- 10 operating with the stoppin of an operated pushber at adesired tuning position upon actuation of a push-button and thesimultaneous rotation of the selector member, a control circuit includedin said receiver and having a normally open switch, and means controlledby said stop pin at its limit of travel to actuate the switch to closedposition.

DUDLEY E. FOSTER.

button to arrest the motion of the selector mem-

